Tight Quarters
Photograph by Brian Skerry

Just three feet wide by 18 feet (five meters) long, the corridor in the main compartment of Aquarius doesn't leave much room for maneuvering. "To make it work right, you have to choreograph your moves," says the New England Aquarium's Ken Mallory, at right. "We feel liberated when we enter the wide open space of the ocean." After swimming like fish, the aquanauts sleep like sardines, stacked in bunks that flank the porthole at the far end of the habitat.